K. Metzler's research while affiliated with University of Münster and other places

... The surface of airless planetary bodies is subject to various processes that lead to changes in its material properties. These include micrometeorite and meteorite impacts and resulting abrasion (e.g., Rüsch and Wöhler, 2022), shattering (e.g., Hörz et al., 1975; and brecciation (e.g., Bischoff et al., 2006Bischoff et al., , 2018Cambioni et al., 2021;Horz & Cintala, 1997;Keil, 1982;Pieters and Noble, 2016;Stöffler et al., 1988), diurnal temperature variations due to the body's rotation (e.g., Delbo et al., 2014;Molaro et al., 2015), and a constant bombardment of protons (e.g., Barghouty et al., 2011;Housley et al., 1974). These processes occurring on different spatial and temporal scales are essential in understanding the evolution of planetary surfaces and the preservation of potentially valuable materials such as organics and ices. ...

Reference:

On the Response of Chondrites to Diurnal Temperature Change—Experimental Simulation of Asteroidal Surface Conditions

... Applying a range of temperatures and humidity levels on polished sections of the H5 chondrite Asuka-10177, the experiments revealed extensive weathering of the Fe-Ni metal grains, but only a minor alteration of troilite and no evidence of mafic silicate alteration. The overall good preservation of Atacama chondrites is further attested by (i) the similar 16 O-rich isotopic composition of Los Vientos 051 among the newly defined CL group (Metzler et al., 2021) and (ii) similar Oisotopic compositions of olivine and pyroxene crystals in Sierra Gorda 009 and Grosvenor Mountains (GRO) 95551, coming from Atacama and Antarctica, respectively (Ivanova et al., 2020). However, in terms of isotopic compositions, highly weathered Antarctic meteorites still exhibit less variability compared to meteorites from hot deserts (Maeda et al., 2021;Pourkhorsandi et al., 2022). ...

Reference:

Dense collection areas and terrestrial alteration of meteorites in the Atacama Desert

... The latter project was also a result of my wish to study some of the meteorites I had found myself. Some projects involved collaborations that went beyond the study of cosmogenic nuclides, such as the consortium formed by Derek Sears on the Fayetteville regolith breccia (Wieler et al., 1989a,b), the work on Almahata Sitta (Riebe et al., 2017c), a meteorite that had fallen in Sudan less than a day after the discovery of its immediate parent asteroid of a few metres size, and the work on meteorites containing cluster chondrite clasts (Müsing et al., 2021). These clasts are characterised by deformed and indented, closely spaced chondrules thought to have accreted within hours or days after they had formed (Metzler, 2012). ...

Reference:

A journey in Noble Gas Cosmochemistry and Geochemistry

... Among different presolar phases, silicates are the most labile to secondary processing, resulting in their significantly lowered abundances (less than 10 ppm) in highly aqueously altered samples (Leitner et al. 2020;Liu et al. 2020b;Barosch et al. 2022a). The abundances of presolar SiC, graphite, and nanodiamond in chondrites seem not sensitive to aqueous alteration (e.g., Liu et al. 2020b; Barosch et al. 2022a;Nguyen et al. 2024) but significantly affected by thermal metamorphism; these presolar phases are inferred to be essentially absent in unequilibrated ordinary chondrites of petrologic type > 3.8 (Huss & Lewis 1995;Huss et al. 2003). ...

Reference:

Presolar grains

... However, CB chondrules are strongly dominated by metal with minor silicate and thus are inferred to have different genesis than the silicate chondrules in normal chondrites (e.g., Krot et al., 2005;Bollard et al., 2015). Hellmann et al. (2020) reported internal 182 Hf-182 W systematics of a macrochondrule from the L5/6 chondrite NWA 819 that corresponds to a model age of 1.4 ± 0.6 Ma after CAIs. These authors also reported 182 Hf-182 W data for metal from the host chondrite that gives a younger model age of~11 Ma after CAIs. ...

Reference:

Early solar system chronology from short-lived chronometers

... The previously best studied meteorite in our sample suite is NWA 5205, a coarse-grained breccia consisting of huge cluster chondrite clasts (up to~10 cm), embedded in matrix (Metzler 2012;Metzler and Pack 2016;Metzler et al. 2019). The mean chondrule sizes vary dramatically between different clasts, indicating chondrule size sorting prior to accretion (Metzler et al. 2019). ...

Reference:

Noble gases in cluster chondrite clasts and their host breccias

... To this end, the Hf-W systematics of enstatite chondrites may hold important clues for better understanding the origin and magnitude of Hf-W fractionations among chondrites. As for ordinary chondrites (e.g., Archer et al. 2019;Hellmann et al. 2019;Kleine et al. 2008), the high metal content of enstatite chondrites makes it possible to determine precise metal-silicate Hf-W isochrons. Furthermore, enstatite chondrites were subject to metal-silicate fractionation between the EH (high Fe) and EL (low Fe) groups (e.g., Sears et al. 1982), which thus may have different Hf/W ratios. ...

Reference:

Hf-W isotope systematics of enstatite chondrites: Parent body chronology and origin of Hf-W fractionations among chondritic meteorites

... Since these works, meteorites have been recognized as objects of scientific importance, and natural history museums worldwide have established invaluable meteorite collections. Despite the recent boom in space exploration, most of our current understanding of the conditions and chronology of the formation of the solar system has been established thanks to the meticulous work of meteorite collection and curation (Heck et al. 2019). ...

Reference:

The Piancaldoli meteorite: A forgotten primitive LL3.10 ordinary chondrite

... High-energy shock events from asteroid impact are the universal geological process on the surface of planets in the solar system (e.g., the Mars, Moon, and Earth; Fassett & Minton, 2013;Osinski & Pierazzo, 2013). On Mars, the continuous shock events of 4.5 billion years can not only change the physical and compositional properties of Martian crustal materials Jaret et al., 2014;Stöffler et al., 2018) but also affect the habitability of Mars (e.g., frustrate the biomolecular components on ancient Mars; Hazael et al., 2016). At present, it is difficult to precisely constrain the shock environment (e.g., shock pressure, shock effect, and shock history) of the Martian surface in the laboratory (because most of the Martian meteorites are altered by impact sputtering; Fritz et al., 2005). ...

Reference:

Quantifying Shock Effects of Mars Sample via Micro‐FTIR Spectra of Plagioclase

... Northwest African (NWA) Sahara is among the well-known areas for meteorite falls, so it received the attention of most of the African scientists where hundreds of meteorites of different types have been collected and recorded. According to Gattacceca et al. (2018), a total of 1868 meteorites were approved by the Nomenclature Committee of the Meteoritical Society in 2017. Among these, the NWA meteorites represent 33% (about 616 meteorites) of the total number of meteorites (Meteoritical Bulletin no 106). ...

Reference:

Frequency-based electric fingerprint and thermal properties of the NWA 869 chondrite